turbo510

I went to check on a friends '02 1.8T, which was down on power and obviously missing on one cylinder. At idle or just above, there was a fairly loud knocking noise, which sounded like it was coming from the head. The cat was also glowing from digesting unburned fuel, and the exhaust was puffing. Leaning over the engine, it sounded to me like cylinder 3, so I disconnected the coil, and the knock was gone. Connnected, it came back. I went to take a video to share, and when restarted, the knock was gone, in fact the engine idled quietly and smoothly. We went for another drive, and it now ran fine.

Could this be a coil failure, but one that was firing constantly? The knock seemed to be serious pre-ignition, not a mechanical defect like stuck valve bucket. Any thought on this guys?

mrmnico

Any engine codes ?